Deuteration isotope effect on nonradiative transition of fac-tris (2-phenylpyridinato) iridium (III) complexes

Deuterated 2-phenylpyridine and coordinated iridium(III) complexes Ir(ppy-h8)n(ppy-d8)3−n (n = 0, 1, 2, 3) have been prepared. Both the relative and absolute phosphorescent quantum yields and the emission decay times of dilute solutions have been studied around room temperature. Phosphorescent quantum yields of fully deuterated Ir(ppy-d8)3 have ranged from 0.80 to 0.93 in several solvents, which are higher than that of normal complex Ir(ppy-h8)3. Ligand deuteration increases the quantum yield. On the other hand solvent deuteration has almost no effect. Nonradiative rate constants show little temperature dependence for the both complexes (knr = 1.4 ± 0.3 × 105 s−1 and 0.95 ± 0.2 × 105 s−1) at 273–308 K.